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<section>
  <article></article>
</section>

*, *:before, *:after{margin: 0; padding: 0;}

section{/**/
  height: 8em;/**/
  width: 8em;/**/
  background: blue;/**/
}

article{/**/
  background: red;/**/
  margin: 2em;/**/
  width: 4em;/**/
  height: 4em;/**/
}